A cryptographic signature is a unique digital code attached to an email or file that verifies the sender’s identity and ensures the content hasn’t been tampered with.
It’s generated using encryption algorithms and private keys, allowing recipients to confirm that a message genuinely comes from the stated source, and that it hasn’t been modified in transit.
In the context of email, cryptographic signatures are most commonly used by DKIM (DomainKeys Identified Mail) to prove message authenticity.
Cryptographic signatures are built on public key cryptography. When an email is sent, the sender’s mail server uses a private key to create a unique signature based on the contents of the message. The recipient’s server then retrieves the sender’s public key (published in DNS) to verify the signature.
If the verification succeeds, the email is confirmed as authentic and unchanged. If it fails, it means the message was either altered or not sent from an authorized source.
This process helps prevent spoofing, phishing, and other email-based attacks by ensuring that messages can be trusted.
Email authentication protocols like DKIM, SPF, and DMARC all rely on cryptographic methods to confirm sender legitimacy.
Without a cryptographic signature, there’s no reliable way to verify that an email claiming to be from your domain truly originated from you, which leaves the door open to impersonation and fraud.
Strong cryptographic validation not only improves security but also enhances email deliverability, as mail providers are more likely to trust messages from properly authenticated domains.
DMARCeye helps organizations make sense of authentication data from DKIM and DMARC reports.
By visualizing how your domain’s cryptographic signatures are being verified across the internet, DMARCeye gives you clarity into who’s sending mail on your behalf, whether it’s properly signed, and when something looks suspicious.
This insight makes it easier to maintain a trusted sending reputation, and to catch configuration issues before they impact deliverability or security.
Sign up for a free trial of DMARCeye today to secure your email domain.
To learn more about DMARC and DMARC-related terms, explore the DMARCeye Glossary.